What is Packet Sniffing and How To Prevent an Attack

Networks transmit data by breaking it into smaller packets. Packet sniffers are used legitimately by network administrators, but they can also be used by network attackers for malicious purposes. It is therefore essential to gain a deeper understanding of packet sniffers to better protect enterprise network security and prevent packet sniffing attacks. Hackers use packet sniffers to carry out network attacks, but it can also provide effective preventive and protective measures to help improve network your security.

What is Packet sniffing？

Packet sniffing is a technique for identifying, reading, and logging data packets that move over a network. This may be performed using either dedicated hardware or software tools, which are frequently used to monitor network traffic and protect against security flaws.

IT professionals can analyze packets delivered via the Transmission Control Protocol/Internet Protocol (TCP/IP) to record and assess network activity such as internet browsing patterns, usernames, and passwords. Furthermore, packet sniffers can detect malicious data, solve network issues, and assess bandwidth use. It assists in identifying and resolving any issues that may hamper network efficiency, ensuring network operation and security.

However, it's important to point out that hackers can use packet sniffers to get critical information from firms. This information frequently includes personal conversations, financial data, and login passwords. In the absence of effective and strong network safety measures, hackers may use packet sniffing to facilitate further harmful operations. Such as when a user downloads a compromised attachment, the hacker may discreetly install a packet sniffer on the device by inserting malicious code among the downloaded packets, allowing them to monitor and modify the data over time.

How to work legally with a packet sniffer?

It is important to note that packet sniffing is illegal when done without authorization, which may violate privacy and security. It is therefore imperative that packet sniffing is only employed in legal and authorised situations, which are as follows:

1. Network Interface Card (NIC) in promiscuous mode:

   Typically, a network interface card (NIC) will only receive packets addressed to it. When set to promiscuous mode, the NIC accepts all network packets, regardless of destination.

2. Capture packets: 
   

   The network monitoring tool records all packets sent over the network. The packets contain information about the data header and load.

3. Parsing packets
   

   Once gathered, the packets are parsed to extract the most useful information. The parsing process evaluates the packet's header information, which includes the source and destination addresses, protocol type, and other relevant data. Furthermore, the parsing step entails the examination of the load information, which includes the actual data delivered.

4. Analyzing the data
   

   The parsed data may be used for a variety of purposes, such as network troubleshooting, performance monitoring, and security analysis. When utilized in conformity with regulatory requirements, network managers can examine packets to detect network problems or improve network performance.

5. Storage and Reporting

   Some sniffer software allows users to preserve recorded packets and create detailed analysis reports.

How do hackers use packet sniffing for attacks?

A packet sniffing attack is a hacker's malicious behavior of capturing and reading data from network traffic using a sniffer. In addition to invasion of privacy, hackers can use the information obtained from sniffing to carry out further attacks, including:

• Infecting networks with viruses or malware
• Hijacking important files with ransomware
• Accessing accounts to steal money and service subscriptions
• Using information to attack organizations

There are two types of such attacks:

• Passive sniffing

  Hackers passively monitor traffic passing through a network hub in a local area network (LAN) or wireless network. This method does not interact with data and is therefore difficult to detect, similar to covert surveillance or eavesdropping, but it has fewer application scenarios because modern networks tend to use switches.

• Active Sniffing
  

  Hackers redirect data streams from switched networks to sniffers by injecting Address Resolution Protocol (ARP) traffic. This allows them to intercept, read, and log packets for sensitive information such as usernames and passwords.

What is the best way to defend against packet sniffing?

To safeguard your organization's network from malicious packet sniffers, we recommend the following measures:

1. Avoid using public Wi-Fi
   

   When travelling, do you often require access to free public Wi-Fi in coffee shops, train stations, or city centers? It is possible that hackers may deploy Wi-Fi sniffers on these unsecured networks to monitor data transmitted over the network, making any device connected to the Wi-Fi more vulnerable to snooping. To safeguard your information, it is advisable to refrain from using unsecured Wi-Fi networks in public locations. Should you be required to use such a network, it is advisable to connect to a VPN (Virtual Private Network) to encrypt your traffic.

   
2. Use encrypted protocols and enable two-factor authentication
   

   Password sniffing is a man-in-the-middle attack in which hackers capture unencrypted packets to obtain password information. The hacker steals this data as it travels from your device to its destination. To prevent this attack, ensure that all network communications use encrypted protocols such as HTTPS and SSL/TLS. Even if a hacker captures a packet, the encryption prevents them from reading the data in transit. Also, add extra layers of security to prevent unauthorized access.

3. Disable any unnecessary web services
   

   Your Internet browser stores information such as saved form data or login details, which provides convenience when logging in to frequently used websites. However, this information can also be used by hackers to obtain this data through packet sniffing. Please note that even if you delete your browser's cookies and history, Google will still save some browsing data. To reduce the likelihood of an attack, it is advisable to close any unnecessary network services and ports.

4. Select reputable software download platforms
   

   Attackers may introduce harmful code into downloaded packets, therefore avoid downloading and opening files from unknown sources. Also, always download software from reliable websites, and keep your operating system, browsers, and other applications up to date to address known security problems.

5. Change session IDs regularly
   

   Servers should routinely update session IDs to avoid utilizing the same ID for an extended length of time. TCP session hijacking, is a packet-sniffing method in which a hacker attacks by obtaining your session ID (a personal number provided by the server during a user's online session). By hijacking legitimate session IDs, hackers can perform “authorized” activities on the network for malicious purposes.

6. Monitor network traffic
   

   ARP sniffing is an attack in which hackers redirect traffic from your IP address to their own IP address by intercepting packets and sending fake messages. To prevent ARP spoofing, you can use a static ARP table in your network and enable the ARP detection feature of your network devices to identify and block suspicious ARP traffic. In addition, regularly inspect network traffic, identify and respond to unusual activity, and use intrusion detection systems (IDS) and intrusion prevention systems (IPS) to enhance network security.

Protect your network with NovaMDR

ForeNova provides 24/7 monitoring and threat detection utilizing advanced security technologies and top-tier professionals to secure your endpoints, networks, cloud services, and identities.

Furthermore, NovaMDR's cutting edge XDR technology can identify and respond to anomalous activity in real time, thereby further enhancing network security.

By combining these measures, NovaMDR can provide your organization with comprehensive network protection against sophisticated network attacks such as packet sniffing.